1. Field of the Invention
The present invention relates to a first-in first-out (FIFO) buffer capable of storing a plurality of data sets having different data lengths, more particularly relates to a FIFO buffer capable of partially erasing data sets.
2. Description of the Related Art
Known in the art is a FIFO buffer (hereinafter referred to as a "FIFO") provided with a memory circuit, a write pointer for specifying an address for writing to that memory circuit, and a read pointer for specifying an address for reading from that memory circuit. This buffer compares the pointer values of the write pointer and the read pointer and detects a full/empty state of the memory circuit to control the writing and reading of data sets.
As will be explained later by reference to the drawings, in a FIFO having this conventional configuration, it is impossible to erase a particular data set or sets among the stored data sets.
Partial erasure of the data sets would become possible by using a plurality of FIFOs. However, in a FIFO which should store therein a plurality of data sets having different data lengths, ordinarily just a single FIFO is used from the viewpoint of storage efficiency. To erase a particular data set in that FIFO, it is necessary to clear out at least all of the data sets to be erased. During this clear out operation, it becomes impossible to write any data set into the FIFO.
As explained above, in a conventional FIFO, there was a problem in that it was not possible to erase a particular data set without clearing out all of the data sets to be erased.